In this paper, the surface structure of poly(L-lactic acid) (PLLA) film modified with gelatin was investigated. ThePLLA film specimens were treated directly with aqueous alkali solution to provide their surfaces with carboxyl groups, sothat these functional groups could become the reactive sites for gelatin immobilization. The functional groups of the PLLAfilms were identified by ATR-FTIR spectra and XPS spectra, the changes in surface morphology were observed by usingenvironmental scanning electron microscopy (ESEM), and the hydrophilicity of modified PLLA films was examined bywater contact angle measurement. Experimental results showed that the gelatin was immobilized with water-solublecarbodiimide (EDC) onto the PLLA film’s surfaces, and the gelatin content on the polymer surface was related to carboxylicgroup formed in the controlled hydrolysis process. Rough surfaces caused by hydrolysis will predominantly favor the adhesion and growth of cell; and the hydrophilicity of these surfaces after the modification procedure is enhanced. In this paper, the surface structure of poly (L-lactic acid) (PLLA) film modified with gelatin was investigated. ThePLLA film specimens were treated directly with aqueous alkali solution to provide their surfaces with carboxyl groups, sothat these functional groups could become the reactive functional fragments for gelatin immobilization. The functional groups of the PLLA membranes were identified by ATR-FTIR spectra and XPS spectra, the changes in surface morphology were observed by usingenvironment scanning electron microscopy (ESEM), and the hydrophilicity of modified PLLA films were examined by water contact angle measurement. Experimental results showed that the gelatin was immobilized with water-soluble carbodiimide (EDC) onto the PLLA film’s surfaces, and the gelatin content on the polymer surface was related to carboxylic groups formed in the controlled hydrolysis process. Rough surfaces caused by hydrolysis will predominantly favor the adhesion and growth of cell; and the hydrophilicity of these surf aces after the modification procedure is enhanced.